Masked officers entered the Moldovan parliament Thursday to handcuff and arrest former Prime Minister Vlad Filat for his alleged part in a $1 billion bank fraud.

Moments earlier, the lawmakers voted to strip Filat of his parliamentary immunity. He was taken in for questioning and can be held for 72 hours before being formally charged or let go.

Moldovan prosecutor general Corneliu Gurin said the disappearance of $1 billion from the country's banking system "caused grave damage to the economic, social and political situation in the Republic of Moldova."

Filat told reporters before his arrest that he was innocent.

"As a citizen, I will cooperate with the investigation with the hope that this will be a fair and correct proceeding," he said. "I will try to prove my innocence."

Filat is head of the Liberal Democrat Party of Moldova — a former Soviet republic — and was the prime minister from 2009 until 2013. He is accused of taking about $250 million from the $1 billion that prosecutors say disappeared from banks last year.

The scandal has severely hurt the economy of what was was already Europe's poorest country, struggling to prove that it is worthy of joining the European Union someday.

Thousands of Moldovans have held round-the-clock protests in Chisinau, demanding that top government ministers resign.